1. Field of the Invention
The present invention relates to an overmolded fenestration building product and its method of manufacture.
2. Background Art
Fenestration building products have been used to allow light into residential, commercial and industrial buildings. The fenestration buildings products typically fit in an opening in the building. Non-limiting examples include windows, doors, doorlites, sidelights, skylights and tubular skylights. The fenestration products will ideally allow light into the building while keeping other environmental elements out. However since the installation of the fenestration building products involves providing an opening in the building, sealing such units has presented a number of challenges.
In a typical fenestration building product installation, the opening is flashed with a sheet or part of a sheet to provide a leaktight seal between the fenestration product's frame and the wall section or door to which it is attached. Many of these fenestration products are fabricated during the installation of the fenestration product. Leaktight seals applied during field installation, which may have initially been effective, often degrade over time and begin to allow leaks of air and water. Minimizing the degradation of the seals or eliminating the sealing points all together, may improve the reliability of fenestration building products in terms of preventing air and moisture leakage.
The use of plastics to consolidate parts in an assembly is well known. Many of the joints which comprise a significant number of sealing points in certain fenestration building products can be eliminated by use of single-piece molded plastics. In general many objects can be overmolded by injecting plastic on to at least part of the edge of the object when it has been pressed between two platens of a mold. Experience has shown though that the use of this technique although satisfactory for many products, such as electrical equipment, poses a number of problems when applied to fragile materials, such as glass and thin sheets of relatively brittle plastic.
Overmolding of glass for a skylight has been disclosed in U.S. Patent Application 2005/0055901 filed by certain inventors of this application. The '901 application discloses a skylight frame molded about an insulated glass unit. The skylight frame assembly includes a frame section which has U-shaped channel molded by reaction injection molding (RIM). The U-shaped channel is adapted to hold one or more panels of glass. The skylight frame is then attached to a curb made by the (RIM) process using very expensive thermoset polyurethane material. The connection of the frame assembly and the curb provides a pathway for wind and water penetration if the seal is not effective.
The skylight of the '901 application does not fully transmit the light because the RIM material absorbs a significant amount of the light due to its relatively low surface reflectivity. This is particularly a problem when dealing with a tubular skylight where the light must travel at least one or more floors to reach the intended room.
What is needed is a building fenestration product that is suitable for all residential, commercial, and industrial uses and which minimizes the pathways that water can enter the building through the openings and which is economical to manufacture. It must also assist in transferring the light efficiently to the interior rooms and in particular in the rooms that are not adjacent to exterior walls or roofs.